Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

851
FXUS63 KLOT 211124
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
624 AM CDT Sat Mar 21 2026

.KEY MESSAGES...

- Early summer-like temperatures are expected this afternoon,
  followed by blustery and sharply colder conditions on Sunday.

- Cooler and drier weather is expected early next week.

&&

.DISCUSSION...
Issued at 248 AM CDT Sat Mar 21 2026

The next 48 hours will be a tale of two seasons, with early
summer temps today tumbling back to late winter temps for
Sunday.

A massive upper-level ridge responsible for widespread record
high temperatures across the southwest CONUS the past couple
days will quickly deamplify into broader WNW flow aloft across
much of the CONUS through the weekend. Light easterly flow early
this morning will increase and veer southwest by early
afternoon in response to a compact low crossing northern
Wisconsin this afternoon. This will advect the unseasonably warm
airmass associated with the ridge northeastward over the area
this afternoon. In fact, 925 hPa temps will near late-March
record values of over 20C late this afternoon (per KILX sounding
climo). If we can mix to 925 hPa, which seems more likely than
not, max temps should at least reach or surpass 80F south of
I-80 and the mid 70s toward the Wisconsin state line. Would not
be entirely surprised to see temps make a run at 80F at Chicago
(far from the daily record of 87F in 2012). The expected deeper
mixing will also foster the development of gusty winds
potentially to 30 mph by sunset, as well as locally elevated
brush fire concerns where rain has been less prevalent the past
couple weeks (e.g. toward east-central Illinois).

The cold front associated with the low passing to the north
today will surge southward late tonight through Sunday morning,
resulting in a blustery, colder, cloudy and possibly damp day on
Sunday. Temps will struggle to climb out of the 40s through the
day, and may remain stagnant in the lower 40s across northeast
Illinois. Additionally, a band of anafrontal precip with perhaps
an embedded elevated thunderstorm is possible, though marginal
mid-level moisture implies that precip chances will be limited
to either drizzle or bands of light rain.

Broader WNW flow across the northern CONUS will take hold
across much of next week, with a continued series of waves
crossing somewhere across the Great Lakes region. Cooler but
seasonable conditions will prevail as high pressure passes north
of the area Monday and Tuesday. A trough passing well to the
north on Tuesday is progged to push a stalling cold front near
or over the region late Tuesday night into Wednesday, with a
stronger trough crossing the Great Lakes region Thursday into
Thursday night. The cold front with Thursday`s system is favored
to still south of the area, leading dry conditions amid colder
temps for Friday.

Kluber

&&

.AVIATION /12Z TAFS THROUGH 18Z SUNDAY/...
Issued at 624 AM CDT Sat Mar 21 2026

- Gusty southwest winds expected this afternoon
- Wind shift to gusty northeast winds and IFR (or lower)
  conditions expected after 06z Sunday morning.

Light southeast winds will become south-southwest and begin
increasing later in the morning. By early afternoon, south-
southwesterly winds will likely gust between 20-30kt until
around sunset. A cold front will move across the terminals
after 06z Sunday with a brief (an hour or two) wind shift to
northwest before the stronger lake enhanced front results in
another shift to gusty northeast winds prior to sunrise Sunday.
Low stratus is expected to follow quickly (less than an hour or
so) behind the wind shift to northeast. Guidance has trended a
bit slower with the lake enhanced front, but given the tendency
for these type of boundaries to move faster than progged, made
no changes to timing with this TAF packate. For now, introduced
IFR CIGS, but certainly possible that CIGS could be LIFR given
the initially very shallow nature of this front.

- Izzi

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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